JQuery: Novice to Ninja- P2

Chia sẻ: Cong Thanh | Ngày: | Loại File: PDF | Số trang:15

lượt xem

JQuery: Novice to Ninja- P2

Mô tả tài liệu
  Download Vui lòng tải xuống để xem tài liệu đầy đủ

JQuery: Novice to Ninja- P2:No matter what kind of ninja you are—a cooking ninja, a corporate lawyer ninja, or an actual ninja ninja—virtuosity lies in first mastering the basic tools of the trade. Once conquered, it’s then up to the full-fledged ninja to apply that knowledge in creative and inventive ways.

Chủ đề:

Nội dung Text: JQuery: Novice to Ninja- P2

  1. xvi Flags . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 373 Settings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 374 Callbacks and Functions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376 $.support Options . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 376 Events . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 Event Properties . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 379 Event Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 DIY Event Objects . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 380 JavaScript Tidbits . . . . . . . . . . . . . . . . . . . . . . Licensed to JamesCarlson@aol.com Appendix B 381 Type Coercion . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 381 Equality Operators . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 382 Truthiness and Falsiness . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 383 Appendix C Plugin Helpers . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 Selector and Context . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 387 The jQuery Stack . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 388 Minification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 389 Index . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 393
  2. Preface No matter what kind of ninja you are—a cooking ninja, a corporate lawyer ninja, or an actual ninja ninja—virtuosity lies in first mastering the basic tools of the trade. Once conquered, it’s then up to the full-fledged ninja to apply that knowledge in creative and inventive ways. In recent times, jQuery has proven itself to be a simple but powerful tool for taming and transforming web pages, bending even the most stubborn and aging browsers to our will. jQuery is a library with two principal purposes: manipulating elements on a web page, and helping out with Ajax requests. Sure, there are quite a few Licensed to JamesCarlson@aol.com commands available to do this—but they’re all consistent and easy to learn. Once you’ve chained together your first few actions, you’ll be addicted to the jQuery building blocks, and your friends and family will wish you’d never discovered it! On top of the core jQuery library is jQuery UI: a set of fine-looking controls and widgets (such as accordions, tabs, and dialogs), combined with a collection of full- featured behaviors for implementing controls of your own. jQuery UI lets you quickly throw together awesome interfaces with little effort, and serves as a great example of what you can achieve with a little jQuery know-how. At its core, jQuery is a tool to help us improve the usability of our sites and create a better user experience. Usability refers to the study of the principles behind an object’s perceived efficiency or elegance. Far from being merely flashy, trendy design, jQuery lets us speedily and enjoyably sculpt our pages in ways both subtle and ex­ treme: from finessing a simple sliding panel to implementing a brand-new user in­ teraction you invented in your sleep. Becoming a ninja isn’t about learning an API inside out and back to front—that’s just called having a good memory. The real skill and value comes when you can apply your knowledge to making something exceptional: something that builds on the combined insights of the past to be even slightly better than anything anyone has done before. This is certainly not easy—but thanks to jQuery, it’s fun just trying.
  3. xviii Who Should Read This Book If you’re a front-end web designer looking to add a dash of cool interactivity to your sites, and you’ve heard all the buzz about jQuery and want to find out what the fuss is about, this book will put you on the right track. If you’ve dabbled with JavaScript, but been frustrated by the complexity of many seemingly simple tasks, we’ll show you how jQuery can help you. Even if you’re familiar with the basics of jQuery, but you want to take your skills to the next level, you’ll find a wealth of good coding advice and in-depth knowledge. You should already have intermediate to advanced HTML and CSS skills, as jQuery uses CSS-style selectors to zero in on page elements. Some rudimentary programming Licensed to JamesCarlson@aol.com knowledge will be helpful to have, as jQuery—despite its clever abstractions—is still based on JavaScript. That said, we’ve tried to explain any JavaScript concepts as we use them, so with a little willingness to learn you’ll do fine. What’s in This Book By the end of this book, you’ll be able to take your static HTML and CSS web pages and bring them to life with a bit of jQuery magic. You’ll learn how to select elements on the page, move them around, remove them entirely, add new ones with Ajax, animate them … in short, you’ll be able to bend HTML and CSS to your will! We also cover the powerful functionality of the jQuery UI library. This book comprises the following nine chapters. Read them in order from beginning to end to gain a complete understanding of the subject, or skip around if you only need a refresher on a particular topic. Chapter 1: Falling in Love with jQuery Before we dive into learning all the ins and outs of jQuery, we’ll have a quick look at why you’d want to use it in the first place: why it’s better than writing your own JavaScript, and why it’s better than the other JavaScript libraries out there. We’ll brush up on some CSS concepts that are key to understanding jQuery, and briefly touch on the basic syntax required to call jQuery into action. Chapter 2: Selecting, Decorating, and Enhancing Ostensibly, jQuery’s most significant advantage over plain JavaScript is the ease with which it lets you select elements on the page to play with. We’ll start off
  4. xix this chapter by teaching you how to use jQuery’s selectors to zero in on your target elements, and then we’ll look at how you can use jQuery to alter those elements’ CSS properties. Chapter 3: Animating, Scrolling, and Resizing jQuery excels at animation: whether you’d like to gently slide open a menu, or send a dialog whizzing across the screen, jQuery can help you out. In this chapter, we’ll explore jQuery’s wide range of animation helpers, and put them into practice by enhancing a few simple user interface components. We’ll also have a quick look at some animation-like helpers for scrolling the page and making elements resizable. Licensed to JamesCarlson@aol.com Chapter 4: Images, Slideshows, and Cross-fading With the basics well and truly under our belts, we’ll turn to building some of the most common jQuery widgets out there: image galleries and slideshows. We’ll learn how to build lightbox displays, scrolling thumbnail galleries, cross- fading galleries, and even take a stab at an iPhoto-style flip-book. Chapter 5: Menus, Tabs, Tooltips, and Panels Now that we’re comfortable with building cool UI widgets with jQuery, we’ll dive into some slightly more sophisticated controls: drop-down and accordion- style menus, tabbed interfaces, tooltips, and various types of content panels. We’re really on a roll now: our sites are looking less and less like the brochure- style pages of the nineties, and more and more like the Rich Internet Applications of the twenty-first century! Chapter 6: Construction, Ajax, and Interactivity This is the one you’ve all been waiting for: Ajax! In order to make truly desktop- style applications on the Web, you need to be able to pass data back and forth to and from the server, without any of those pesky refreshes clearing your inter­ face from the screen—and that’s what Ajax is all about. jQuery includes a raft of convenient methods for handling Ajax requests in a simple, cross-browser manner, letting you leave work with a smile on your face. But before we get too carried away—our code is growing more complex, so we’d better take a look at some best practices for organizing it. All this and more, in Chapter 6.
  5. xx Chapter 7: Forms, Controls, and Dialogs The bane of every designer, forms are nonetheless a pivotal cornerstone of any web application. In this chapter, we’ll learn what jQuery has to offer us in terms of simplifying our form-related scripting. We’ll learn how to validate forms on the fly, offer assistance to our users, and manipulate checkboxes, radio buttons, and select lists with ease. Then we’ll have a look at some less conventional ways of allowing a site’s users to interact with it: a variety of advanced controls like date pickers, sliders, and drag and drop. We’ll round it off with a look at modal dialogs in the post-popup world, as well as a few original nonmodal notification styles. What a chapter! Chapter 8: Lists, Trees, and Tables Licensed to JamesCarlson@aol.com No matter how “Web 2.0” your application may be, chances are you’ll still need to fall back on the everyday list, the humdrum tree, or even the oft-derided table to present information to your users. This chapter shows how jQuery can make even the boring stuff fun, as we’ll learn how to turn lists into dynamic, sortable data, and transform tables into data grids with sophisticated functionality. Chapter 9: Plugins, Themes, and Advanced Topics jQuery is more than just cool DOM manipulation, easy Ajax requests, and funky UI components. It has a wealth of functionality aimed at the more ninja-level developer: a fantastic plugin architecture, a highly extensible and flexible core, customizable events, and a whole lot more. In this chapter, we’ll also cover the jQuery UI theme system, which lets you easily tailor the appearance of jQuery UI widgets to suit your site, and even make your own plugins skinnable with themes. Where to Find Help jQuery is under active development, so chances are good that, by the time you read this, some minor detail or other of these technologies will have changed from what’s described in this book. Thankfully, SitePoint has a thriving community of JavaScript and jQuery developers ready and waiting to help you out if you run into trouble. We also maintain a list of known errata for this book, which you can consult for the latest updates; the details are below.
  6. xxi The SitePoint Forums The SitePoint Forums1 are discussion forums where you can ask questions about anything related to web development. You may, of course, answer questions too. That’s how a discussion forum site works—some people ask, some people answer, and most people do a bit of both. Sharing your knowledge benefits others and strengthens the community. A lot of interesting and experienced web designers and developers hang out there. It’s a good way to learn new stuff, have questions answered in a hurry, and have a blast. The JavaScript Forum2 is where you’ll want to head to ask any questions about jQuery. Licensed to JamesCarlson@aol.com The Book’s Web Site Located at http://www.sitepoint.com/books/jquery1/, the web site that supports this book will give you access to the following facilities: The Code Archive As you progress through this book, you’ll note a number of references to the code archive. This is a downloadable ZIP archive that contains each and every line of example source code that’s printed in this book. If you want to cheat (or save yourself from carpal tunnel syndrome), go ahead and download the archive.3 Updates and Errata No book is perfect, and we expect that watchful readers will be able to spot at least one or two mistakes before the end of this one. The Errata page4 on the book’s web site will always have the latest information about known typographical and code errors. The SitePoint Newsletters In addition to books like this one, SitePoint publishes free email newsletters, such as the SitePoint Tech Times, SitePoint Tribune, and SitePoint Design View, to name 1 http://www.sitepoint.com/forums/ 2 http://www.sitepoint.com/forums/forumdisplay.php?f=15 3 http://www.sitepoint.com/books/jquery1/code.php 4 http://www.sitepoint.com/books/jquery1/errata.php
  7. xxii a few. In them, you’ll read about the latest news, product releases, trends, tips, and techniques for all aspects of web development. Sign up to one or more SitePoint newsletters at http://www.sitepoint.com/newsletter/. The SitePoint Podcast Join the SitePoint Podcast team for news, interviews, opinion, and fresh thinking for web developers and designers. We discuss the latest web industry topics, present guest speakers, and interview some of the best minds in the industry. You can catch up on the latest and previous podcasts at http://www.sitepoint.com/podcast/, or subscribe via iTunes. Licensed to JamesCarlson@aol.com Your Feedback If you’re unable to find an answer through the forums, or if you wish to contact us for any other reason, the best place to write is books@sitepoint.com. We have a well-staffed email support system set up to track your inquiries, and if our support team members are unable to answer your question, they’ll send it straight to us. Suggestions for improvements, as well as notices of any mistakes you may find, are especially welcome. Acknowledgments Earle Castledine I’d like to thank the good folks at Agency Rainford for running Jelly (and getting me out of the house), Stuart Horton-Stephens for teaching me how to do Bézier Curves (and puppet shows), Andrew Tetlaw, Louis Simoneau, and Kelly Steele from Site- Point for turning pages of rambling nonsense into English, the Sydney web com­ munity (who do truly rock), the jQuery team (and related fellows) for being a JavaScript-fueled inspiration to us all, and finally, my awesome Mum and Dad for getting me a Spectravideo 318 instead of a Commodore 64—thus forcing me to read the manuals instead of playing games, all those years ago. Craig Sharkie Firstly, I’d like to thank Earle for bringing me onto the project and introducing me to the real SitePoint. I’d met some great SitePointers at Web Directions, but dealing
  8. xxiii with them professionally has been a real eye-opener. I’d also like to thank my wonderful wife Jennifer for understanding when I typed into the wee small hours, and my parents for letting me read into the wee small hours when I was only wee small. Lastly, I’d like to thank the web community that have inspired me—some have inspired me to reach their standard, some have inspired me to help them reach a higher standard. Conventions Used in This Book You’ll notice that we’ve used certain typographic and layout styles throughout the book to signify different types of information. Look out for the following items. Licensed to JamesCarlson@aol.com Code Samples Code in this book will be displayed using a fixed-width font, like so: A Perfect Summer's Day It was a lovely day for a walk in the park. The birds were singing and the kids were all back at school. If the code is to be found in the book’s code archive, the name of the file will appear at the top of the program listing, like this: example.css .footer { background-color: #CCC; border-top: 1px solid #333; } If only part of the file is displayed, this is indicated by the word excerpt: example.css (excerpt) border-top: 1px solid #333; If additional code is to be inserted into an existing example, the new code will be displayed in bold:
  9. xxiv function animate() { new_variable = "Hello"; } Also, where existing code is required for context, rather than repeat all the code, a vertical ellipsis will be displayed: function animate() { ⋮ return new_variable; } Some lines of code are intended to be entered on one line, but we’ve had to wrap Licensed to JamesCarlson@aol.com them because of page constraints. A ➥ indicates a line break that exists for formatting purposes only, and should be ignored: URL.open("http://www.sitepoint.com/blogs/2007/05/28/user-style-she ➥ets-come-of-age/"); Tips, Notes, and Warnings Hey, You! Tips will give you helpful little pointers. Ahem, Excuse Me … Notes are useful asides that are related—but not critical—to the topic at hand. Think of them as extra tidbits of information. Make Sure You Always … … pay attention to these important points. Watch Out! Warnings will highlight any gotchas that are likely to trip you up along the way.
  10. 1 Chapter Licensed to JamesCarlson@aol.com Falling in Love with jQuery So you have the coding chops to write lean, semantic HTML—and you can back it up with masterful CSS to transform your design ideas into gorgeous web sites that enthrall your visitors. But these days, you realize, inspiring designs and impeccable HTML alone fall short when you’re trying to create the next Facebook or Twitter. So, what’s the missing piece of the front-end puzzle? It’s JavaScript. That rascally scripting language, cast as the black sheep of the web development family for so many years. JavaScript is how you add complex behaviors, sophisticated interactions, and extra pizazz to your site. To conquer the sleeping giant that is JavaScript, you just need to buckle down and spend the next few years learning about programming languages: functions, classes, design patterns, proto­ types, closures ... Or there’s a secret that some of the biggest names on the Web—like Google, Digg, WordPress, and Amazon—will probably be okay about us sharing with you: “Just use jQuery!” Designers and developers the world over are using the jQuery library to elegantly and rapidly implement their interaction ideas, completing the web de­ velopment puzzle.
  11. 2 jQuery: Novice to Ninja In the following chapter we’ll have a look at what makes jQuery so good, and how it complements HTML and CSS in a more natural way than our old friend and bitter enemy: plain old JavaScript. We’ll also look at what’s required to get jQuery up and running, and working with our current sites. What’s so good about jQuery? You’ve read that jQuery makes it easy to play with the DOM, add effects, and execute Ajax requests, but what makes it better than, say, writing your own library, or using one of the other (also excellent) JavaScript libraries out there? First off, did we mention that jQuery makes it easy to play with the DOM, add effects, Licensed to JamesCarlson@aol.com and execute Ajax requests? In fact, it makes it so easy that it’s downright good, nerdy fun—and you’ll often need to pull back from some craziness you just invented, put on your web designer hat, and exercise a little bit of restraint (ah, the cool things we could create if good taste were not a barrier!). But there are a multitude of notable factors you should consider if you’re going to invest your valuable time in learning a JavaScript library. Cross-browser Compatibility Aside from being a joy to use, one of the biggest benefits of jQuery is that it handles a lot of infuriating cross-browser issues for you. Anyone who has written serious JavaScript in the past can attest that cross-browser inconsistencies will drive you mad. For example, a design that renders perfectly in Mozilla Firefox and Internet Explorer 8 just falls apart in Internet Explorer 7, or an interface component you’ve spent days handcrafting works beautifully in all major browsers except Opera on Linux. And the client just happens to use Opera on Linux. These types of issues are never easy to track down, and even harder to completely eradicate. Even when cross-browser problems are relatively simple to handle, you always need to maintain a mental knowledge bank of them. When it’s 11:00 p.m. the night before a major project launch, you can only hope you recall why there’s a weird padding bug on a browser you forgot to test! The jQuery team is keenly aware of cross-browser issues, and more importantly they understand why these issues occur. They have written this knowledge into the library—so jQuery works around the caveats for you. Most of the code you write
  12. Falling in Love with jQuery 3 will run exactly the same on all the major browsers, including everybody’s favorite little troublemaker: Internet Explorer 6. This feature alone will save the average developer a lifetime of headaches. Of course, you should always aim to keep up to date with the latest developments and best practices in our industry—but leaving the task of hunting down obscure browser bugs to the jQuery Team (and they fix more and more with each new version) allows you more time to implement your ideas. CSS3 Selectors Making today’s technologies cross-browser compliant is all well and good, but jQuery also fully supports the upcoming CSS3 selector specification. Yes, even in Licensed to JamesCarlson@aol.com Internet Explorer 6.0! You can gain a head start on the future by learning and using CSS3 selectors right now in your production code. Selecting elements you want to change lies at the heart of jQuery’s power, and CSS3 selectors give you even more tools to work with. Helpful Utilities Also included is an assortment of utility functions that implement common functions useful for writing jQuery (or are missing from JavaScript!): string trimming, the ability to easily extend objects, and more. These functions by themselves are partic­ ularly handy, but they help promote a seamless integration between jQuery and JavaScript which results in code that’s easier to write and maintain. One noteworthy utility is the supports function, which tests to find certain features are available on the current user’s browser. Traditionally, developers have resorted to browser sniffing—determining which web browser the end user is using, based on information provided by the browser itself—to work around known issues. This has always been an unsatisfying and error-prone practice. Using the jQuery supports utility function, you can test to see if a certain feature is available to the user, and easily build applications that degrade gracefully on older browsers, or those not standards-compliant. jQuery UI jQuery has already been used to make some impressive widgets and effects, some of which were useful enough to justify inclusion in the core jQuery library itself.
  13. 4 jQuery: Novice to Ninja However, the jQuery team wisely decided that in order to keep the core library fo­ cused, they’d separate out higher-level constructs and package them into a neat library that sits on top of jQuery. That library is called jQuery User Interface (generally abbreviated to just jQuery UI), and it comprises a menagerie of useful effects and advanced widgets that are accessible and highly customizable through the use of themes. Some of these features are illustrated in Figure 1.1. Licensed to JamesCarlson@aol.com Figure 1.1. A few jQuery UI widgets Accordions, sliders, dialog boxes, date pickers, and more—all ready to be used right now! You could spend a bunch of time creating them yourself in jQuery (as these have been) but the jQuery UI controls are configurable and sophisticated enough that your time would be better spent elsewhere—namely implementing your unique project requirements rather than ensuring your custom date picker appears correctly across different browsers! We’ll certainly be using a bunch of jQuery UI functionality as we progress through the book. We’ll even integrate some of the funky themes available, and learn how to create our own themes using the jQuery UI ThemeRoller tool.
  14. Falling in Love with jQuery 5 Plugins The jQuery team has taken great care in making the jQuery library extensible. By including only a core set of features while providing a framework for extending the library, they’ve made it easy to create plugins that you can reuse in all your jQuery projects, as well as share with other developers. A lot of fairly common functionality has been omitted from the jQuery core library, and relegated to the realm of the plugin. Don’t worry, this is a feature, not a flaw. Any additional required function­ ality can be included easily on a page-by-page basis to keep bandwidth and code bloat to a minimum. Thankfully, a lot of people have taken advantage of jQuery’s extensibility, so there Licensed to JamesCarlson@aol.com are already hundreds of excellent, downloadable plugins available from the jQuery plugin repository, with new ones added all the time. A portion of this can be seen in Figure 1.2. Figure 1.2. The jQuery plugin repository Whenever you’re presented with a task or problem, it’s worth checking first to see if there’s a plugin that might suit your needs. That’s because almost any functionality you might require has likely already been turned into a plugin, and is available and ready for you to start using. Even if it turns out that you need to do some work yourself, the plugin repository is often the best place to steer you in the right direc­ tion. Keeping Markup Clean Separating script behavior from page presentation is best practice in the web devel­ opment game—though it does present its share of challenges. jQuery makes it a
  15. 6 jQuery: Novice to Ninja cinch to completely rid your markup of inline scripting, thanks to its ability to easily hook elements on the page and attach code to them in a natural, CSS-like manner. jQuery lacks a mechanism for adding inline code, so this separation of concerns leads to leaner, cleaner, and more maintainable code. Hence, it’s easy to do things the right way, and almost impossible to do them the wrong way! And jQuery isn’t limited to meddling with a page’s existing HTML—it can also add new page elements and document fragments via a collection of handy functions. There are functions to insert, append, and prepend new chunks of HTML anywhere on the page. You can even replace, remove, or clone existing elements—all functions that help you to progressively enhance your sites, thus providing a fully featured experience to users whose browsers allow it, and an acceptable experience to Licensed to JamesCarlson@aol.com everyone else. Widespread Adoption If you care to put every JavaScript library you can think of into Google Trends,1 you’ll witness jQuery’s exponential rise to superstardom. It’s good to be in the in crowd when it comes to libraries, as popularity equates to more active code devel­ opment and plenty of interesting third-party goodies. Countless big players on the Web are jumping on the jQuery bandwagon: IBM, Netflix, Google (which both uses and hosts the jQuery library), and even Microsoft, which now includes jQuery with its MVC framework. With such a vast range of large companies on side, it’s a safe bet that jQuery will be around for some time to come—so the time and effort you invest in learning it will be well worth your while! jQuery’s popularity has also spawned a large and generous community that’s sur­ prisingly helpful. No matter what your level of skill, you’ll find other developers patient enough to help you out and work through any issues you have. This caring and sharing spirit has also spread out to the wider Internet, blossoming into an en­ cyclopedia of high quality tutorials, blog posts, and documentation. 1 http://www.google.com/trends/
Đồng bộ tài khoản